An internal combustion engine system for a vehicle includes an internal combustion engine, ICE, operable on a low cetane fuel and having a cylinder at least partly defining a combustion chamber and an ignition source for the low cetane fuel; a fuel injector for injecting the low cetane fuel into the combustion chamber; an ignition improver device in fluid communication with the fuel injector and further configured to supply an ignition improver fluid to the low cetane fuel; a control unit configured to selectively operate the ICE in a spark ignition, SI, mode and a compression ignition, CI, mode. The control unit determines an ICE operating condition and controls the ignition improver device to supply a given amount of ignition improver fluid to the low cetane fuel on the basis of said determined ICE operating condition.

A gasoline compression ignition engine is operated in two modes. In a one mode of operation the engine is operated with a firing fraction of one, corresponding to all of the cylinders being active, working cylinders. In a second skip fire mode of operation a firing fraction of less than one may be used under conditions, such as a low load condition, to improve efficiency. The skip fire mode of operation may also be selected in part based on other considerations, such as maintaining an exhaust temperature conducive for efficient catalytic converter operation or limiting cylinder output variability.

A compression ignition (diesel) engine uses two or more fuel charges during a combustion cycle, with the fuel charges having two or more reactivities (e.g., different cetane numbers), in order to control the timing and duration of combustion. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot). At low load and no load (idling) conditions, the aforementioned results are attained by restricting airflow to the combustion chamber during the intake stroke (as by throttling the incoming air at or prior to the combustion chamber's intake port) so that the cylinder air pressure is below ambient pressure at the start of the compression stroke.

A control device for a compression ignition engine includes a controller configured to operate an engine body by compression ignition combustion when the engine body operates in a compression ignition range. When the engine body operates in a low load range with a load lower than a predetermined load in the compression ignition range, the controller sets a time of fuel injection with the fuel injection valve in a first half of a compression stroke or earlier, and allows the ozonator to introduce the ozone into the cylinder. When the engine body operates in the low load range, the controller controls an ozone concentration to be lower at a higher speed than at a low speed.

Disclosed is a fuel injection control system for a single-cylinder diesel engine, comprising: a set of operating condition sensors including an accelerator pedal position sensor and a cooling water temperature sensor, an input signal interface capable of receiving an input signal from the operating condition sensors, a control unit connected to the input signal interface, and a rotational speed sensor provided at a camshaft or starting shaft of the single-cylinder diesel engine. The rational speed sensor is connected to the control unit via a rotational speed correction circuit. The control system can easily and quickly determine the rotational speed and operating stroke of the single-cylinder diesel engine, so as to quickly determine the fuel injection quantity and injection timing of the single-cylinder diesel engine in real time.

A control device for a compression ignition engine includes a controller configured to operate an engine body by compression ignition combustion when the engine body operates in a predetermined compression ignition range. When the engine body operates in a predetermined high load range of the compression ignition range, the controller maximizes a filling amount of the cylinder using a gas state adjustment system, and lowers an EGR ratio so that the air-fuel mixture in the cylinder is lean with an excess air ratio λ higher than 1 in a lower speed range, and maximizes the filling amount of the cylinder, and increases the EGR ratio so that the air-fuel mixture in the cylinder has the excess air ratio λ of 1 or lower in a higher speed range than the lower speed range.

An internal combustion engine system for a vehicle includes an internal combustion engine, ICE, operable on a low cetane fuel and having a cylinder at least partly defining a combustion chamber and an ignition source for the low cetane fuel; a fuel injector for injecting the low cetane fuel into the combustion chamber; an ignition improver device in fluid communication with the fuel injector and further configured to supply an ignition improver fluid to the low cetane fuel; a control unit configured to selectively operate the ICE in a spark ignition, SI, mode and a compression ignition, CI, mode. The control unit determines an ICE operating condition and controls the ignition improver device to supply a given amount of ignition improver fluid to the low cetane fuel on the basis of said determined ICE operating condition.

A piston for use in a GDCI engine cooperates with the wall of a cylinder defined in the engine and with a cylinder head to define a combustion chamber. The surface of the piston that faces the cylinder head defines a bowl that is configured to receive fuel that is dispensed from a fuel injector that is located in the cylinder head substantially along the central axis of the cylinder. The bowl is configured such that substantially all of the injected fuel associated with a combustion event reaches a localized equivalence ratio greater than 0.0 and less than or equal to 1.2 at a time immediately preceding initiation of the combustion event.

In an internal combustion engine which performs a homogeneous lean combustion mode and a stratified lean combustion mode, there is provided a new internal combustion engine control device capable of obtaining a stable combustion state by decreasing influences of delay of an air flow and a degree of change of a transient state and smoothly performing switching between the homogeneous lean combustion mode and the stratified lean combustion mode. Accordingly, in the present invention, when switching between the stratified lean mode in which a compression stroke injection is performed by a direct injection injector 7 and the homogeneous lean combustion mode in which an intake stroke injection is performed by the direct injection injector 7 is performed, a predetermined delay time t is provided from at least a switching operation of a tumble control valve 6, a switching operation between the compression stroke injection and the intake stroke injection is performed, and the delay time t is set so as to correspond to a magnitude of the degree of change L of the transient state. A switching timing between the compression stroke injection and the intake stroke injection is controlled according to the flow delay of an air control system such as the tumble control valve 6 and the degree of change L of the transient state, and thus, it is possible to improve combustion stability in a combustion chamber.

A control system for a compression-ignition engine is provided, which includes the engine, a spark plug, a fuel injection valve, an air-fuel ratio control valve, and a control unit. A geometric compression ratio of the engine is 14:1 or above. The control unit includes a processor configured to execute an air-fuel ratio controlling module for, when the engine being in a given operating state is detected, controlling the air-fuel ratio control valve to bring the air-fuel ratio of the entire mixture gas to a given lean air-fuel ratio that is larger than a stoichiometric air-fuel ratio, and an spark plug controlling module for, after this control, outputting the control signal to the spark plug to perform the ignition at a given ignition timing so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites. The given ignition timing is stored in a memory.